Production of stable fuel oil



March 20, 1956 D. T. ROGERS 'Er Ax.

PRODUCTION OF STABLE FUEL OIL Filed March 3l, 1951 zr Bru/enters NMODQU n all-nul to Esso Research and Engineering Company, a corporation of Delaware Application March-sil, 19st, serai Nts-.218,574

7 claims. (ci. 44-76) The present inventionvis concerned with anovel composition consisting of al fuel oil containing hydrocarbons derived from cra-cking. operations and containing particular constituents as stabilizersvfor the` fuel oil. The in- Vention is also concerned with animproved process for the production' of thesev novel fuel: compositions. In accordance with the present invention, the constituents to be employed as stabilizers consist of anv alkali or alkaline earth nieta-l salt of= an alkyl phenol sulphide in combination with the residues obtained by distillation of acid treatedl and neutralized lubricating oil derived from naphthenic crudc'oils.

The invention is particularly concerned with hydrocarbon mixtures known. as fuel oil of the nature employed in various burner systems. Diesel fuels, or. domestic and industrial heating oils are examples of such fuel oils. Fuel oilsv may be derived from. petroleum by a variety of method-s including. straighty distillation from cru'd'e petroleum oil, and thermal or catalytic cracking of petroleum oil fractions.

It has' been' found thatr fuel oil-s consisting completely or in part of cracked stocks are characterized by an undesirable instability giving rise to the formation of sediment. As a result, suehfuel oi-lsmay cause clogging of iilters', orifices, or conduits associated with the burner systems in which they are employed. Therefore, in accordance with the present. invention.. it is proposed to process thefuel oil and to employ certain. specific additivesto overcome thesev difficulties.- Thepresent invention may be readily understood by reference to the drawing illustrating a preferred embodiment of the invention. This drawing illustrates an integrated. refinery operation for the production of heating oils.y of superior quality.

Referring specically to the drawing,v a naphthenic type crude oil, as for example, a Colombian crude?. is introduced into stilly 1- by means of feed line 2.- Distillationy zone l may comprise any number and arrangement of distillation stages. Temperature and pressure conditions in stilll are adjusted to remove overhead, by means of line 3, hydrocarbon constituents boiling below l the motor fuel boiling range. A.. naphtha fraction boiling Within. the motor fuel boiling. rangeis removed by means of line d, while a virgin heating oilr fraction is removed by means of line 5. These streams may be handled or further processed4 in any manner desired. Alight or low boiling lubricating oil distillate is removed from pipe still 1 by means of line 6 while a heavy or high-boiling lubricating oil distillate is removed by means of line 7. A. heavy side stream distillate fraction is removed from the pipe still by means of liney 3' and is introduced into a thermal or catalytic cracking zone 9i.

The heavy lubricating oil fraction 'removed from zone 1 by means of line 7 is introduced into an a'cid treating zone lit) wherein the same is contacted with a suitable mineral acid. The fresh acid is' introduced by means of line 11 whilev the' spent' acid is removed by means of line i2'. Acid treatingl zone' lll may comprise any suitable number and arrangement of stages.

The acid treated oil' nited States Patent O ICC justed to remove lubricating oiloverhead by means of line 21 while a bottoms high boiling fraction is removed by means of line 22.

Catalytic cracking zone 9 may comprise aconventional regenerator and reaction Zone. A gas fraction is segregated by means of line 23 While a cracked' naphtha is removed by means of line 24.y A bottoms fraction is` removed by means of line 25 andiy a cracked heating oill fraction by means of line 26. In accordance with the present invention, there is combinedv with the cracked heating oil fraction a portion of the bottoms fraction segregated from zone 20y by means of line 22. This fraction is added to the cracked ,heating oil by means of line 27. The metal salt of alk-yl phenol sulde is incorporated in the fuel oil by means of line 28 While the finished heating oil product is removed from the system by means of line 29.

As will be brought out,l it is a` preferred feature in blending the bottoms of still 2'0 witli the cracked heating oil of line 26 to specially'` process the still bottoms; To achieve this it is preferred to dilute tlie still bottoms of line 22' with gas oil introduced' through line 30'. The mixture of still bottoms and gas oil is then. filtered in zone 31 and the filtered mixture' of gasoil and still bottoms is then. conducted ythrough lin'e. 27 for adinixture with the cracked heating oil.

The invention is broadly concerned with an improved heating oil product and is more particularly concerned with an improved process' for securing this product. In accordance with the present invention, still residues segregated in the distillation of a heavy lubricating oil' dis'- tillate are added to the heating oil' fraction in combination with a metal salt of alkyl phenolsuliid'e.

Temperature and pressure conditions in the distillation of the naph'theni'c crude.. may vary appreciably. For instance, a typical light lubricating oil distillate has a vi'scosity of from y60 to 80 Saybolt seconds Universal at 100 F. The distillation of this fraction at' l0 mm. mercury absolute pressure is about as follows:

F. Initial boiling point 210 5% l285 10% 308 50% 401 492 Final boiling point 522 Y The light lubricating oil distillate is" preferably treated with sulfuric acid of" about 9'0- fo 95%- concentration. When using 931% acid?, approximately isf pounds o'f acid per gallons of oil is utilized.

on the other hand, the concentration of ttieacid used when treating a heavy lubricating oil distillate is in the range from about 95% to 100%. When using 98% acid, the amount used varies from about pounds to 135 pounds of acid, preferably about pounds of acid per 100 gallons of heavy lubricating oil distillate.

The sludge is removed and the oil is then preferably treated with an excess of caustic. The concentration of the caustic may vary from 30 Baume to 50 Baum. The amount of excess caustic should be such that about 0.05 weight percent of excess sodium hydroxide is present in the oil as it is introduced into the linishing pipe still.

The operating conditions of the pipe still 20 may be varied appreciably. Generally, the oil is heated to a ternperature above 750 F., preferably to a temperature of about 785 F., at which the pressure is about 17 pounds absolute. This fraction is then ashed into a vacuum finishing pipe still (pipe still 20) at a pressure of about 125 mm. of mercury absolute. The temperature in a typical operation of the flash zone is about 673 F. The pressure at the top of the pipe still in a typical operation is about 56 mm. of mercury absolute while the temperature is about 414 F. The bottoms pressure is about 175 mm. mercury absolute while the temperature is about 666 F. One method of operating is to introduce steam into coil 17 as well as into the bottom of zone 20. A typical operation requires introduction of about 1260 pounds of steam per hour to coil 17 and about 1350 pounds of steam per hour into zone 20 when utilizing a feed rate to zone 20 at about 7500 barrels per day of heavy lubricating oil distillate.

The catalytic cracking zone from which the cracked heating oil is produced comprises a conventional one. For example, it is well known in the art to produce cracked naphthas and cracked heating oils by a iluidized solids catalytic operation wherein the cracked product comprises constituents boiling in the motor fuel boiling range, as for example below about 430 F., and heating oil fractions. The cracked product also comprises normally gaseous constituents, as for example, those containing 3 carbon atoms and less in the molecule. The fluidized solids technique may be employed for processing feed fractions, as for example, gas oils, heavy residuums and other feed stocks for the production of hydrocarbon fractions boiling in the motor fuel boiling range. The system of a uidized solids cracking operation comprises a reaction zone and a regeneration zone, employed in conjunction with a fractionation zone. The operation of the reaction zone and the regeneration zone is preferably as follows: Y

An overflow pan is provided in the regeneration zone at the desired catalyst level. The catalyst overows into a withdrawal line which preferably has the form of a U- shaped seal leg connecting the regeneration zone with the reaction zone. The feed stream introduced is usually preheated to a temperature in the range from about 500 to 650 F. in exchangers in heat exchange with regenerator flue gases which are removed overhead from the regeneration zone, or with cracked products. The heated feed stream is withdrawn from the exchangers and introduced into the reactor. The seal leg is usually suiciently below the point of feed oil injection to prevent oil vapors from backing into the regenerator in case of normal surges. Since there is no restriction in the overow line from the regenerator, satisfactory catalyst ow will occur due to the difference in density of the uidized solids in the system. Spent catalyst from the reactor flows through a second U-shaped seal leg from the bottom of the reactor into the bottom of the regenerator. The rate of catalyst ow is controlled by injecting some of the air into the catalyst transfer line to the regenerator.

The pressure in the regenerator may be controlled at the desired level by a throttle valve in the overhead line from the regenerator. Thus, the pressure in the regenerator may be controlled at any desired level by a throttle valve which may be operated, if desired, by a differential pressure controller. If the pressure differential between the two vessels is maintained at a minimum, the seal legs will prevent gases from passing from one vessel into the other in the event that the catalyst ilow in the legs should cease.

The reactor and the regenerator may be designed for high velocity operation involving linear supercial gas velocities of from about 2.5 to 4 feet per second. However, the superficial velocity of the upflowing gases may vary from about l to about 5 and higher. Catalyst losses are minimized and substantially prevented in the reactor by the use of multiple stages of cyclone separators. The regeneration zone is provided with cyclone separators. Two or more stages of cyclone separators are usually employed.

Operating temperatures and pressures may vary appreciably depending upon the feed stocks being processed and upon the products desired. Operating temperatures are, for example, in the range from about 800 to 1000" F., preferably about 850-950 F., in the reaction zone. Elevated pressures may be employed, but in general pressures below lbs. per sq. in. gauge are utilized. Pressures in the range from 1 to 30 lbs. per sq. in. gauge are preferred. A catalyst holdup corresponding to a space velocity of l to 20 weight per hour of feed per weight of catalyst is utilized. A preferred ratio is 2 to 4. Catalyst to oil ratios of about 3/1 to 10/ 1, preferably about 6/1 to 8/1 by weight are used.

The catalyst used in the catalytic cracking operation, in accordance with the present invention, is any one of the conventional cracking catalysts. These catalysts are chosen from the oxides of metals of groups II, III and IV of the periodic table. A preferred catalyst comprises silica-alumina wherein the weight per cent of the alumina is in the range from about 5 to 20%. Another preferred catalyst comprises silica-magnesia where the weight per cent of the magnesia is about 5% to 20%. These catalysts may also contain a third constituent, as for example, ThOz, W03, M003, BeO, BizOz, CdO, U03, B203, SnOz, F6203, V205, M110, CrzOs, Cao, T1203, MgO and C6203 present in the concentration from 0.05% to 0.5%. The size of the catalyst particles is usually below about 200 microns. Usually at least 50% of the catalyst has a size in the range from about 20-80 microns. Under these conditions with the superficial velocities as given, a fluidized bed is maintained; in the lower section of the reactor, a dense catalyst phase exists while in the upper area of the reactor a disperse phase exists.

As pointed out, in accordance with this invention, it has been established that the instability of cracked heating oils may be substantially overcome by utilizing small quantities of the distillation residue of an acid treated and neutralized heavy lubricating oil in conjunction with a suitable metal salt of alkyl phenol sulfide. The lubricating oil residue is secured by distilling a heavy lubricating oil distillate containing an excess of sodium hydroxide, although other alkali metal hydroxides may be employed, if desired.

Heating oils which may be stabilized by these additives are hydrocarbon mixtures of which more than about 10% consist of stocks derived from thermal or catalytic cracking operations. More precisely still, the base stocks may be characterized as petroleum fractions containing a proportion of cracked stocks greater than 10% and falling within A. S. T. M. specication D97548T for diesel fuel oils (grades Nos. l-D to 4-D inclusive) and A. S. T. M. specification D-396-48T for fuel oils (grades Nos. l to 6 inclusive). Thus, on the ow plan illustrated, the oil to be stabilized may be the cracked heated oil of line 26 or may be a blend of this oil with the virgin heating oil of line 5.

One component of the stabilizing additive comprises an alkali or alkaline earth metal salt of an alkyl phenol sulphide or a phosphorus sulphide reaction product thereof.

An illustration of this type of compound Vis y.barium isooctyl phenol sulphide. With reference to the barium isooctyl-phenol Isulphide, or itsre'quivalent to be included, it may he noted that .these -are the .types of compounds disclosed in U. S. Patents No. 2,362,291 and No. 2,451,345. The compounds of this nature which maybe employed maybe explicitly defined as the neutral `or Ibasic alkali or alkaline earth metal salts of an alkyl phenol monoor cli-sulphide, or the phosphorus sulphidelreaction product thereof. The metal ion may thus consist of sodium, potassium, barium, calcium, strontium, lithium, or magnesium. The alkyl group maybe a paraffinic group of normal, branched, or cycloparaffinicnature"containing 5 to 22 carbon atoms and preferably containing 8 to 18 carbon atoms. Other substituent'groups such as halogen and amino groups may be associated with the alkyl group. Phosphorus poma-sulphide is 'the preferred sulphide of sulfur to be employed in deriving reaction products of the indicated sulphides. As these compounds are now well known to the art, no further description of them is considered necessary. It may be noted that compounds of the class described are commercially available. In general they are prepared as a concentrate of the active ingredient in a heavy oil vehicle. However, in the data which follows, it is to be understood the quantities indicated represent the amount of active ingredient exclusive of the vehicle in which it is contained.

The invention may be more fully understood by the lfollowing example illustrating the same:

EXAMPLE Still bottoms, recovered from the distillation over caustic of acid treated heavy lubricating oil fractions exhibit a synergistic effect, when employed in combination with metal phenol sulphides to inhibit sediment formation in heating oil compositions. Data illustrating this synergism are given in the following table:

Heating oil stability tests (16 hours at 210 F.)

Mg. Insolu- Additive (Weight Percent) l ble Sludge] one 27 0.35% Still Bottoms 2 50 0.012% Barium Iscoctyl Phenol Sulfide 52 0.004% Barium isooctyl Phenol Sulflde+0.10% Still Bottoms 3 0.005% Potassium isooctyl Phenol Sulfide 22 0.005% Potassium Isooctyl Phenol Sultld +0 Still Bottoms 0 0.005% Barium Isooctyl Phenol Sulde+0.002% Calcium Petroleum Sulfonate 27 0.005% Barium Isooetyl Phenol Snliide+0.002% Calcium Petroleum Sulfonate+0.l0% Still Bottoms l 0.008% Barium Isooctyl Phenate-Sulfur Reaction Product. 48 0.008% Barium Isooetyl Phenate-Suliur Reaction Product +0.10% Still Bottoms 6 0.008% Barium Isooctyl Phenol Sulfide-Phosphorus Pentasulfide Reaction Product 49 0.008% Barium isooctyl Phenol sulfide-Phosphorus Pentasulfide Reaction Product+0.10% Still Bottoms. 1

1 Pipe still bottoms diluted with an equal volume oi gas oil and filtered. 2 Analysis of still bottoms:

Ash content, percent 4. 72 Sodium, percent 2.17 Neutralization No 0.0

Experiments were also made to evaluate the preferred processing technique of this invention in which the still bottoms were diluted with gas oil and filtered prior to addition `to Lthe 'oil to tbe .,stabilized In employing .this

.technique .the still bottoms are Ydiluted with about l to 4 volumes of gas oil boiling in the range of about 350 F. to .65.0 F. Preferably, the .pipe still ,bottoms are diluted with .about 2 volumes .of `gas oil. The filtrate provides a gas oil concentrate of still bottoms and may be added directly yto the hydrocarbon fraction to be stabilized 'in combination with .the metal alkyl phenol sulfide.

The following table shows the effect of diluting still bottoms with gas oil .and then -filtering the mixture.

As shown in the table, raw pipe still bottoms when blended in a heating oil provided a sediment of more than 124 mg. per 600 g. of fuel oil. When these pipe still bottoms were diluted with gas oil in equal parts and filtered, the same concentrate of pipe still bottoms provided a sediment of only 50. VGreater dilutions of the pipe still bottoms reduce this sediment further indicating an optimum dilution of about 2 parts of gas oil for 1 part of still bottoms. This effect was also verified on blending the raw pipe still bottoms with alkyl phenol sulfide and heating oil as compared to a similar blend employing the refined still bottoms. It was found that appreciably less sediment was obtained in the case of the fuel oil containing the refined still bottoms.

As disclosed herein therefore, the present invention concerns a stabilized fuel oil obtained by incorporating minor quantities of caustic neutralized pipe still bottoms and a metal alkyl phenol sulfide. The invention is particularly applicable to the stabilization of fuel oils, but may also be employed in the stabilization of other hydrocarbon fractions such as lubricating oils, greases, etc. It is apparent that the compositions of this invention may include any of the conventional additives ordinarily employed. The compositions of this invention are compatible with use of such conventional additives.

What is claimed is:

1. A stabilized fuel oil composition including fuel oil constituents derived from cracking operations characterized by inclusion of about 0.02 to 0.50% of the residue obtained by the distillation of a heavy lubricating oil obtained from a naphthenic crude oil by steps including sulfuric acid treatment, sludge removal, and caustic neutralization, and about 0.002 to 0.04% of a cornpound selected from the group consisting of alkali and alkaline earth metal salts of an alkyl phenol sulfide.

2. The composition defined by claim 1 in which the said residue is obtained by distilling overhead about to 95% of the said treated lubricating oil.

3. The composition defined by claim l in which the said salt of an alkyl phenol sulfide constitutes barium isooctyl phenol sulfide.

4. The process for preparing a stable fuel oil comprising the steps of distilling a naphtherlic crude oil to provide a heavy lubricating oil distillate and a reduced crude oil distillate fraction, treating said lubricating oil distillate with sulfuric acid, removing the sludge therefrom, neutralizing the said treated distillate with au excess of caustic, and distilling a substantial portion to obtain a residue, and cracking said reduced crude oil distillate to obtain a cracked heating oil fraction, and thereafter blending about 0.02 to 0.50% of the said residue with said cracked heating oil fraction together with about 0.002 to 0.04% of a compound selected from the group consisting of alkali and alkaline earth metal salts of an alkyl phenol sulfide.

5. The process defined by claim 4 in which the said residue prior to blending is diluted with a low-boiling hydrocarbon fraction and is then filtered.

6. The process defined by claim 4 in which said cracking of the reduced crude oil distillate constitutes catalytic cracking.

7. A composition consisting essentially of a fuel oil base containing at least about 10% of stocks derived from thermal or catalytic cracking operations and about 0.02 to 0.50% of the residue obtained by the distillation of a heavy lubricating oil by steps including sulfuric acid treatment, sludge removal, and caustic neutralization, and about 0.002 to 0.04% of a compound sclected from the group consisting of alkali and alkaline earth metal salts of an alkyl phenol sulfide.

References Cited in the le of this patent UNITED STATES PATENTS 2,033,145 Morrell Mar. 10, 1936 2,362,291 Winning Nov. 17, 1944 2,451,345 McNab et al Oct. 12, 1948 2,527,987 Caron et al. Oct. 31, 1950 OTHER REFERENCES 

1. A STABILIZED FUEL OIL COMPOSITION INCLUDING FUEL OIL CONSTITUENTS DERIVED FROM CRACKING OPERATIONS CHARACTERIZED BY INCLUSION OF ABOUT 0.02 TO 0.50% OF THE RESIDUE OBTAINED BY THE DISTILLATION OF A HEAVY LUBRICATING OIL OBTAINED FROM A NAPHTHENIC CRUDE OIL BY STEPS INCLUDING SULFURIC ACID TREATMENT, SLUDGE REMOVAL, AND CAUSTIC NEUTRALIZATION, AND ABOUT 0.002 TO 0.04% OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF ALKALI AND ALKALINE EARTH METAL SALTS OF AN ALKYL PHENOL SULFIDE. 